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Rate and Regulatory Matters (Narrative-Missouri) (Details)	1 Months Ended	3 Months Ended					12 Months Ended
	Nov. 30, 2023 USD ($)	Sep. 30, 2024 MWh	Dec. 31, 2023 MWh	Mar. 31, 2023 MWh	Dec. 31, 2022 MWh	Sep. 30, 2022 MWh	Dec. 31, 2027 USD ($)	Dec. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($) MWh	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Public Utilities, General Disclosures [Line Items]
Capital expenditures										$ 4,319,000,000	$ 3,597,000,000	$ 3,351,000,000
Revenues										$ 7,623,000,000	7,500,000,000	7,957,000,000
Natural gas
Public Utilities, General Disclosures [Line Items]
Percentage of energy sourced from renewable resources	100.00%
Ameren Missouri
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh										102
Cass County, Boomtown, and Huck Finn Solar Project Purchase Price										$ 1,000,000,000
Capital expenditures										$ 2,712,000,000	1,760,000,000	1,690,000,000
Ameren Missouri \| Rush Island Energy Center
Public Utilities, General Disclosures [Line Items]
Costs to be securitized	$ 476,000,000
Amortization of regulatory asset	$ 15
Ameren Missouri \| Solar generation facility
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh										500
Ameren Missouri \| Generation Facilities
Public Utilities, General Disclosures [Line Items]
Capital expenditures										$ 1,700,000,000
Ameren Missouri \| Maximum
Public Utilities, General Disclosures [Line Items]
Percentage of energy sourced from renewable resources										100.00%
Ameren Missouri \| Electric \| Pending Rate Case
Public Utilities, General Disclosures [Line Items]
Cumulative rate increase										$ 446,000,000
Percent of requested return on equity										10.25%
Percentage of requested equity capital structure										52.00%
American Missouri Proposed Average Annual Rate Base										$ 13,900,000,000
MoPSC Staff recommended rate increase (decrease)										$ 384,000,000
MoPSC Staff's recommended ROE										9.74%
MoPSC Staff's recommended capital structure										52.00%
MoPSC Staff's recommended rate base										$ 13,900,000,000
Months to complete a rate proceeding										11 months
Ameren Missouri \| Electric \| Minimum \| Pending Rate Case
Public Utilities, General Disclosures [Line Items]
Percentage of High Prairie costs challenged by the MoOPC										25.00%
Ameren Missouri \| Electric \| Maximum \| Pending Rate Case
Public Utilities, General Disclosures [Line Items]
Percentage of High Prairie costs challenged by the MoOPC										45.00%
Ameren Missouri \| Build-transfer \| Solar generation facility
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh			300		200	150
Ameren Missouri \| Development-transfer \| Solar generation facility
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh			150
Ameren Missouri \| Self-build \| Solar generation facility
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh			50	50
Ameren Missouri \| Self-build \| Natural Gas Generation Facility
Public Utilities, General Disclosures [Line Items]
Amount of Megawatts \| MWh		800
Ameren Missouri \| Natural gas \| Pending Rate Case
Public Utilities, General Disclosures [Line Items]
Cumulative rate increase										$ 40,000,000
Percent of requested return on equity										10.25%
Percentage of requested equity capital structure										52.00%
American Missouri Proposed Average Annual Rate Base										$ 531,000,000
Months to complete a rate proceeding										11 months
Ameren Missouri \| MEEIA 2019 \| Electric
Public Utilities, General Disclosures [Line Items]
Revenues										$ 13,000,000	$ 12,000,000	$ 22,000,000
Ameren Missouri \| MEEIA 2024 \| Electric \| Forecast
Public Utilities, General Disclosures [Line Items]
Energy efficiency investments in MEEIA 2019 programs							$ 22,000,000	$ 51,000,000
Percentage of MEEIA energy efficiency goals achieved								100.00%
Incentive award if energy efficiency goals are achieved							$ 2,000,000	$ 5,000,000	$ 5,000,000